Electrically operated windlass



June 16, 1931.

R. ECK 1,810,821

ELECTRIGALLY OPERATED WINDLASS File ad July 20, 1927 INVENTOR. RICHARD.ECK

ATTORNEY Brennan non, or

Patented June 16,- 1931 ELECTRICALLY orn Application filed July 20,1927, Serial No.

My invention relates to a new method of and apparatus for controlling oractuating an electrically operated windlass of a-lifting plant andresides more particularly in adapting three-phase asychronous motors forthe purpose. Generally speaking, three-phase asynchronous motors are notadapted at the present stateof the art, for satisfactory use in liftingapparatus, because they do net allow ofany ample control of the liftingspeed as required in foundry-cranes, mounting cranes and: the like. Ithas been su gested heretofore to overcome this drawbac byemploying twoasynchronous motors in connection wlth a balancing gear, for actuatingthe Windlass and to start in practice, one of the motors only in orderto impart to the load a certain low speed, and to then increase thelifting speed to the maximumlimit by starting the other motor.

This suggestion, however, is objectionable on account of thenecessity ofstarting the motors. under load. 1 The disadvantages resulting therefromare considerable and mainly reside in the necessity for the-developmentof a high starting torque by the motor and the employment "ofcorrespondingly high starting currents and variations 0 voltagetherewith-at the switching-on operation, so that the first motor usuallystarts up with an intermittent motion or jerks and the security inservice is thereby seriously impaired. 9

1 The'chief object of my invention is to remedy thisdefect. Withthisobject in view I control, while employing two asynchronous motors and abalancing gear for driving the rope drum, the lifting speed in a mannerthat the two motors are started at the same time but in such a directionof rotation as to neutralize or balance the rotary movements '1 thereofunder the action of the said balancing rem The Windlass, therefore, atfirst in at rest and thetwomotors will start withoutload. For thepurpose of acceleratgear.

ting the load the revolving speed of the one motor then is reduced tozero and thereuponincreased again, in the opposite direction, to

themaximum value. In order to cause the load or work to be lifted asgently astpossibly can be done with' DBESDEN, GERMANY, ASSIGNOR on exams'ro r nmmucnanonr RICHARD GZBEL, 0F DRESDEN, GERMANY RATED wmnLAss207,251, and in Germany J'u1y'2, 1927.

an apparatus of this'character, and as is required particularly in, thehandling of delicate molded and cast articles, adropof the revolvingspeed of the controlling motor is accomplished, in accordance with thepresent lnvention, by subjecting it to a braking efi'ect produced byreversing the direction of current suppliedgthereto, but, at the sametime, causing the drop to be effected in a curve of greatest possibleflatness by applying to the shaft of the controlling or regulating motoran additional turning effort by means of an auxiliary power medium i.e., the auxiliary motor 8, acting in opposition to the braking effectaforesaid of the newly introduced current and which will tend tomaintain the original revolving speed. .To this end, as small auxiliarym otor, above referred -to, will be employed and is connected to thecontrolling or regulating motoreither'directly or by any suitableindirect means. By the alternate action of this reversed current,supplied'to the current or regulatin motor and the'ppposing rotatingeffort of t e auxiliary power medium, the acceleration of the load canbe graded in a most accurate and delicate manner.

With the above recitedfobj ect in view, reference is had to thefollowing specification and drawings in which'there are exhibited twoexamples or embodiments of suitable de vices and mechanisms for carryingout my improved method but which are in no way intended as a limitationupon the scope of the appended claim as it is to be clearly understoodthat variations and modifications which H fairly fall within the truescope of said claim may be resorted to when found expedient.

n the accompanying drawings forming a part of this specification andshowin diagrammatically, for purposesof exemp ification, a preferredform and manner in which the invention may be embodied and practised,but without limiting the claimed invention to such illustrativeinstances:

Figure 1 is a side viewof the apparatus or mechanism for carrying outthe new method of controlling or regulating-the operation of a windlasswithout the use of an auxiliary motor;

Figure 2 is a sectional view, taken on the line A-B in Figure 1; and

Figure 3 is a View similar to Figure l, but showing a modified form ofthe invention wherein an auxiliary motor is employed for the purpose setforth.

Referring to Figures 1 and 2, a denotes the rope drum of the Windlassmounted and adapted to be driven by a suitable intermediate gearcomprising, in the shown instance, two intermeshing toothed wheels I)and 0. The shaft d of the wheel ,0 is subjected to the action of a brakea controlled by a braking magnet f duly connected with a source ofelectric energy, and the shaft d is driven by the motors 7c and 5through the intermediary agency of the members 9, h and 2', as Willbeclearly understood on inspection of Figure 1. The rim of the member orwheel hpossesses teeth on t e inner and on the outer circumference anthe member or pinion i on the shaft of the motor 7:: engages with theouter teeth of the wheel 72, whilst intermediate pinions 9 and g looselymounted on horizontal arms or pins ofthe member'ordisk g mesh with theinner teeth of the Wheel h. The two pinions g and g are driven inopposite directions. by a pinion Z engaging therewith and keyed to theshaft of the motor Z.

The one of the two motors k and Zis driven in lifting direction and theother one is driven in lowering direction. When the two motors run atequal speed the action thereof will be neutralized or balanced and theWind'- lass is at rest. --When it is desired to lift a load -or work,the turning momentum or rewolv:

ing speed'of the lowering motor is reduced and when a oad or work hungupon the hook of the re e, is--to be lowered, the revolving speed of t elifting motor is decreased. If the one or the other motor is at rest,the load or work will be moved at half speed, and if the same motor isthen causedto run at increased speed in the opposite direction, the loador work will be given or net 7. The wiring n and 0 connects the drum a.ably are of like m with the stators'of the two motors, respectively,whilst the wiring n and o connects 'the same with the rotors thereof,respectively. 'In operation, the two motors, which preferpower and equalspeed, are to be started at the same time. The rotary speed which thedisk 7 and the shaft (1 would be given by the motor Z, if the motor hwere at rest, is neutralized or balanced by the rim of the wheel hmoging in opposite direction when the motor k is running so as v todrive the wheel by means of the pinion 2',

and the shaft d and disk h remain at rest from the first. .The motorsthus run on no creased accordingly.

load. In order to prevent, in case of a suspended load or work, thelowering of the same, the brake remains closed at first. The speed of,the one or the other motor is then reducedby switching in resistancesand at the same time the brake e is deenergized. The difference betweenthe speeds of the two motors is transmitted to the disk 9 and causes therope drum a to revolve through the intermediary of the shaft (Z and thegearing 0, b.

In the modification illustrated in Figure 3, the rope drum a and thepinion c are keyed -to'the shaft (Z and the brake a, controlled by themagnet f, is mounted as before to exert a braking action on the shaftwhen required. The toothed wheels 6 and b are in engagement with pinionsi and 2' to form a balancinggear, since the latter are keyed to one andthe same shaft 'w mounted to revolve in a suitable bearing provided forthe purpose in the main wheel 6, while the cooperating wheels k and kare keyed to the shafts of the two motors 7c and Z, respectively. Now,when the two motors run in the same direction, the shaft 'w will runidle, while the main *wheel I) and consequently the ro e drum a motor Zand in the same direction as the main wheel 6, the speed of the latterwill be in- The controlling and regulating device .m providedswithsuitable resistances r as shown in Figure 3, is, as regards constructionand arrangement, similar to that illustrated in Figure 1. The. wires nand 0 connect the resistances with the stators of thetwo motors,respectively, and the wires 11. and 0 connect the resistances with therotors of the two mbtors, respectively. In this modification, as shownin Figure 3, an auxiliar motor s is coupled with'the motor I: anseparate wires u. and y are provided to connect the stator and the rotorof the motor 8, respectively; with the controlling resistances r.

ing the wheels h i and 723, z" to run at e ual speed whilst theauxiliary motor 3 is at rst left switched off, so that the resultingeffect of the'speed of the two motors is'neutralized or balanced at thiscondition of the, plant, with the brake switched on. Thereupon, thespeed of one of the two motors, say the motor k, is reduced by thebraking efiect produced by reversing the current supplied to the runningmotor Jo, and at the same time the brake 0 is switched off and theauxiliary motor 8 started to run in the same direction of the runnin-motor so that the gear comprising the W eels b and c, and consequentlythe rope drum (1 will be actuated. The motor Z works for lifting and themotor k for lowering purposes, and that under the actionof the loadmomentum, while the friction of the gearings and the reversed current inthe motor k acts in opposition to the said load momentum. As soon as thetwo last-mentioned forced (friction and counter or re versed current)effect a balance of the said load momentum, the motor lc will tend tocome to rest. Inorder to prevent the motor. Z0 from actually coming torest too quick or abruptly and the load from being accelerated by jerks,the auxiliary motor s is now switched on to assist in behalf of the loadmomentum. The motor 8 thus acts in opposition to the counter or reversedcurrent of the motor 70 and enables the operator to retard at will thedrop of the speed of the motor is and to thereby adjust or adapt thecourse of the starting curve of the Windlass in a delicate manner inaccordance with the requirements of the service.

As the counter or reverse current supplied to the motor kis furtherincreased by switching off the resistances r, such increase willautomatically diminish the speed and overcome the action of the motor 8as the speed of the motor 70 continues to drop off, the load or workwill be lifted and at an increased rate of lift the quicker theresistances r are cut out of circuit'with the motor 70. As soon as themotor 7: stops, the load or work will move with half-speed and theauxiliary motor 8 is switched off after having thus performed itsservice, and remains ready for use in assisting the motor In afterwardsas required.

As the counter or reversed current continues to increase, the motor isthenwill be correspondingl accelerated but in its oplposite revolvingirection and thus the loa p or work-attains its highest speed of lift.

When a load or work, suspended from the hook, is to be lowered firsttheone motor and thereafter also the other motor will be drivenmenees,the one motor 1 tor and subsequently jointly and by the load soas to act like asynchronous generators to return current into thenetwork. As soon as the lowering movement comwill run above synchronismvand the other one below synchronism wherefrom-aminimum lowering speedensues. At the same time, a braking action will at once he brought aboutby the one generabtv both enerators any desired s ow or uick lowermgmovement will thus' be obtained in accordance with the difference in theof the two motors.

What I claim is In a device of the class described, a windlass, abalancin gearing operatively coupled to said win lass, an asynchronousmotor 'operatively coupled to said balancing gearing,a secondasynchronous motor also operatively coupled to said balancing gearing,means for controlling said motors whereby both of the same are firstcaused to run at full speed in such directions with relation to eachother that the Windlass remains at rest under the action of thebalancing gearing thereon, said control means being operable to retardthe rotary motion of one of said motors to zero, then to reverse thesame and thereafter to accelerate it in the opposite direction to causethe Windlass to move a load thereon, said retarding movement of saidmotor being accomplished by the application to the same of a countercurrent, and an auxiliary motor coupled to the last named of said motorsto counteract the drop of the rotary speed of the same during theretarding movement thereof aforesaid. I

RICHARD EGK.

